rad fan

[thedog28]

Hi guys and gals,


i have noticed that when i first start up , choke on , warm up, its not long b4 the rad fan kicks in, soon as i put it in gear tho, fan switches off. All seems well, never over heats etc. Ive only had the bike since last august so not sure if this is a normal thing. Its a 1000 on an 03 plate.


Thanks in advance.


Rob

[fireblake]

Thanks for asking that, my bike does the same too so i don't think it's a problem?

[ghostbiker]

They all do that sir!

[paul1606]

As above tis normal start it up blip the throttle fan kicks in

[Ghoti]

It is a safety device to stop the fan motor from overheating when stationary.

[pilgrim]

Its a pain in the bollocks when you're trying to warm the bike up in winter before you set off!!!
Been meaning to fit a cut off switch since about 2005 but not got round to it yet :b
And I know I'll forget to flip it back when I'm ready to go :o

[purplebear7]

No need for a cut off switch ..

I'm a bit out of date on Gen 1s by several years .. but I seem to recall that the 'cold' fan will stop once you put the bike into gear.  It will then stay off until the engine is up to temp and it needs cooling.

No doubt someone will put me straight if I'm wrong  :rolleyes

Stay Safe    Polar Bear

[thedog28]

sweet, ty guys just the info i wanted to hear lol. get rid of the ugly sprt rack and ill be as happy as a pig

[PieEater]

Its a pain in the bollocks when you're trying to warm the bike up in winter before you set off!!!
Been meaning to fit a cut off switch since about 2005 but not got round to it yet :b
And I know I'll forget to flip it back when I'm ready to go :o

To me this doesn't make sense - if the fan is controlled by a thermostat it will kick in when the engine reaches a specific temperature. The only difference the outside air temperature will make is how long the engine takes to warm up to the specific temperature and so how long it takes for the fan to kick in. The fan isn't stopping the engine from reaching a decent operating temperature it's preventing it from overheating past the warm-up temperature. Fitting a fan cut-off switch is potentially going to allow your bike to overheat past the point that it was designed to operate at, which is not something I would reccomend. If you're having problems in cold weather maybe check the de-icing circuit isn't clogged if you haven't already, I've removed mine as I don't ride in cold weather and when I did I noticed that connectors were fairly corroded meaning a blockage wouldn't be out of the question.

[PieEater]

It is a safety device to stop the fan motor from overheating when stationary.

More of a device to stop the fan motor from overheating when on the move - the fan is needed when the bike is stationary to stop the engine overheating, the fan cuts out when you put the bike in gear as it's assumed you'll soon be on the move so the fan is no longer required.

[tomjimtom]

I always thought the fan came on at tickover out of gear to just check it's working, it's obviously not cooling anything when you're warming up, it also won't be imparing the warm up of the engine, the thermostat won't open channels to the rad until it's at a certain temperature.

[pilgrim]

Funny thing is ...
The fan kicks in after the same amount of time no matter what the air temperature is, summer or winter. It also seems to be linked to the revs.
If it stays below about 1500 rpm while on choke it doesnt come on, but even slightly above that and wwwhhhhhhhhhhhhiiiiiirrrrrrrrrrrrrrr! If you set off as soon as the fan kicks in and flip the choke off, you can tell its not up to operating temperature. All stuttery and lumpy :\
Or if you flip the choke off as soon as the fan kicks in and dont set off, tickover drops way too low, which says to me that its not up to operating temp.
I seem to have a vague memory of reading somewhere that its set to come on as a test that the fan is working, and as far as I can tell, it kicks in before the engine is up to temp, or there is any danger of overheating.
Not saying I'm right, just a different angle on the thing 
It still bugs me though. Have to park the bike on the side stand at work cos of uneven ground, so I cant knock it into gear to turn the fan off cos
of the side stand cut out. :\

[pilgrim]

Note to self:
Type faster and brew up less :lol

[PieEater]

Thinking aloud - testing that the fan is operating wouldn't need the complex behaviour of waiting for an initial period then having the fan operate until such time as the bike is put into gear, it would just involve the fan coming on when the engine starts and turning off when the ECU knows it is spinning. Having had a read of the Haynes manual (the owners manual has nothing to say about the fan) the thermostat stops coolant flowing through the system until the engine is at it's normal operating temperature at which point it opens allowing the heated coolant through the system. In the thermostat housing is a switch that operates the fan and temperature warning light. My guess would be that the fan kicks in when the thermostat opens allowing the initial rush of heated coolant through the system. I have no idea why the fan doesn't come on under 1500 rpm I think mine does but when warming the engine I normally have mine sat above this.
Personally I don't have the stuttery / lumpy behaviour when first moving off, I still think this could be caused by carb icing if it only happens in cold weather and is eliminated by allowing extra warming time.

[Ghoti]

Although the engine does not warm up quickly, the header pipes do. The fan motor is near the header pipes. The fan come on after a short while if the bike is in neutral and the throttle is shut (based on revs) to stop the fan motor from overheating from the headers.

When moving the wind will do the job. On the basic electronics on the Fazer, this is the best/easiest solution to protect the fan.

[PieEater]

Being intrigued by all the theories I phoned the helpful people at Yamaha UK and spoke with one of their technical bods. First thing he said was that if you're warming the bike to the point that the fan is kicking in you're waiting too long to ride it, you need to get going before it kicks in as by that point it's already overheating. Second thing he said was that the fan kicks in to protect the fans plastics (not the motor) from the heat from the headers, it's not to aid the cooling system as I thought.
So there you have it (and the reason not to fit a cut-off switch).

[Falcon 269]

Second thing he said was that the fan kicks in to protect the fans plastics (not the motor) from the heat from the headers, it's not to aid the cooling system as I thought.
So there you have it (and the reason not to fit a cut-off switch).

Hmmm, not entirely persuaded by that explanation.  

Surely if the fan plastics were heat-vulnerable, the fan would kick in whenever the motor is idling for more than a set period, regardless of coolant temp?  For that matter, why fit heat-vulnerable plastics to a radiator fan?  Doesn't make sense to me.

When I pull into a town after blatting around in mountains, my headers are scorching hot, as is the rest of the motor and parts in close proximity.  The fan doesn't come on immediately, though ... it waits until the coolant has reached 98c.

My '99 R1 doesn't do this and there's a lot more heat retained behind the fairing than the Fazer.

[PieEater]

Doesn't make any sense to me either but I can't argue with the horses mouth.
I thought 'modern' plastics could withstand a fair amount of heat and wouldn't have expected to Yamaha to have fitted stuff that wasn't up to the job. It makes more sense that the fan comes on triggered by the thermostat sensor to aid the cooling system but I asked him to confirm this wasn't the case three times and each time he said no it was to protect the fan plastics !!!!

[Falcon 269]

And it also says 'Kellogg's Cornflakes' on the side of a bus, but that doesn't mean they sell them...

[thedog28]

a lot of good thoughts and ideas there, plus side is, its normal operation and not a fault i though it might be, so im happy    thanks guys